Method of covering articles



Feb. ll, 1936. w, s, rrrcQMB 2,030,160

' lm'rnon or covsnruo ARTICLES Filed April 4,;1954

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" Jv /4 d dv /5 (ll/I vPatented Feb. v11, 1936 UNITED. STATES PATENT OFFICE 2.03am mz'rnon or covsamo n'ncxns William S. Tltcomb, Andover, Mala., alllgnor to Shoe Lace Company, Boston, Mass., a corporationof Maine This invention relates to improvements in methods of covering rod-like articles, and is illustrated herein with reference to applying an insulating covering about an electric conductor.

Many uses for rod-like articles such as wires, for example, require that they shall be provided with a coverim which is substantially vimpervious and has sumcient flexibility to permit of its being bent without breaking or cracking. Such covering may be made either separate from the article on which it is to be used but adapted to be put thereon, or it may be formed integrally with an indefinite length of `the material from which the article is to be made.

The invention is concerned with the formation on a rod-like article such as an electric conductor, for example, of an insulating covering which not only meets the above-named prerequisites but also cannot readily, or will not in the normal use of such artlcle or conductor, be removed from it.

Accordingly, the invention contemplates that improvement in methods of covering rod-like articles which consists in first coating the article with a volatile solvent and then, before the coating of solvent has evaporated, applying a fabric covering to the coated article, some orv all of the strands of which covering are solublev in the solvent with which the article has 'been coated. -If desired, the stepof coating the article may be carried out by applying thereto a solution ofthe material of which the soluble strands of the covering are composed. As a result of practising either of these methods, the solvent or solution permeates the covering as the latter is applied as about the article and causes the soluble strands ofthe covering not only to dissolve, at least partially, and to coalesce, but also to be bound tenaciously to the article itself by a solidified solution ofthe dissolved strands 40 I have discovered that strands made of cellulose derivative fibers such, for example, as cellulose acetate fibers, are suitable for making a covering such as that referred to above, this substance being readily soluble in acetone. It has been found desirable in some instances, moreover, to combine with strands of acellulose derivative, strands of substantially insoluble bers such, 'for example, as cotton or other cellulose fibers, vwhich the cellulose derivative web in its 50 dissolved state readily permeates and, when reaolidifled, completely encases.

Great strength and imperviousness may be obtained in a covering of the type under consideration by repetition of the. above-mentioned methoda and thereby superimposing a plurality of layers of covering, and causing the contiguous layers, as well as their strands,l to be united to each other by a homogeneous web of the material'of which the soluble strands are composed.

As mentioned above, an important application 5 of the present invention is in connection with electric conductors having coverings of the type described above. Accordingly, the invention has been illustrated herein with reference to coverings for electric conductors but, aswill be pointed 10 out below, the invention may have other applications and is not to be limited to that referred to herein, which has been selected merely for i1lus` trative purposes, and which will now be described with reference to the drawing, in which,`. 15

Fig. 1 illustrates a fabric covered conductor a portion of the covering of which has been treated in accordance with the invention;

Fig. 2 is a sectional view of, the covered conductorshown in Fig. 1 as taken along the line 20 II-II of Fig. 1; v

Fig. 3 is a view in perspective illustrating a covering alone of the type which is illustrated as applied about a conductor shown in Fig. l;

Fig. 4 illustrates another form of fabric cover- 25 ing contemplated by the invention as applied about a pair of conductorsf Fig. 51s a sectional view, taken along the line V-V of Fig. 4; and

Figs. 6 and '7 are sectional views illustrating 30 coverings comprising a plurality of layers of fabric.

Various uses of wire either in great lengths or in relatively short lengths, both of which are intended to be included ,by the term rod-like article as employed herein, require that the wire yshall have a covering. This covering may be made separately as an article of manufacture and adapted to be applied about a rod-like article or wire (as in the case of the spaghetti used in some radio receiving apparatus) or it may-be formed about the article. y l

. Referring now to Fig. 1, a rod-like article or wire il has a covering consisting of rubber insulation I2 anda tubular fabric sheath Il, which 45 preferably is braided about an indefinite length of the rubberinsulated wire I0, or which, if desired, can be applied in relatively short lengths about short lengthsof the wire. The sheath I4 may be a fabric of any appropriate form whether woven or braided, but as herein illustrated is a so-called diamond braid each strand of lwhich passes rst over and then under two other strands, The sheath Ilfis composed entirelyof Strands s the fibres of which are readily soluble.

Suchstrands may'be made from a cellulose derlvative such as cellulose acetate, for example. .This material can be readily dissolved in many volatile Y fluids such, for example, as acetone and diethylene oxide,which are suitablefor use in carryingout the invention, as will be explained below.

'I'he sheath I4 is next treated with a solvent of the type referred to, as, by immersion or by beingsprayed, suiiiciently to cause the strands s to be at least partially dissolved. The material thus dissolved from the strands s thoroughly permeates them and lh the interstices between them, giving the sheath. as treated, a structure consisting of the remaining portion of the braid thestrands of which are united by a homogeneous webformed of the material dissolved from the soluble strands s. As indicated. in Fig. 2, the strands s when dissolved coalesce to a great extent,-1mdergo a slight reduction in thickness owing to the' leveling of the ridges of the fabric structure and .the

filling in of the interstices and, being thus united to each other by the solid material remaining when the volatile solvent has entirely evaporated,

form a substantially homogeneous and impervious sheath I5. Such a sheath or covering I6, separate tion of the treatment, the quantity of solvent employed and the nature or condition of the solvent.-

The solvent may, if desired, contain a plasticizer,

the covering illustrated in Fig. 4.

for example di-butyl phthalate or tri-cresyl phosphate, in order to toughen and improve the resiliency of the covering.

While Figs. 1 and 2 illustrate a covering all 'of the strands of which are composed of soluble bers, it may be desiredin some instances to employ both soluble and insoluble strands. 'Such a covering Il isillustratedin Figs. 4 and 5 as being applied about'a pair of conductors 2l Vhaving rubber insulating coverings 22. In Fig. 4 all of the strands which extend upwardly from right to left are made of soluble fibers s while the other strands i are made from fibers which are insolu" ble, or substantially so, in the solvent for the soluble strands; but it is to be understood that the particular proportion of strands having soluble bers and other strands having insoluble bers may be variedas desired. That is. if desired each set of strands may be composed partly of soluble and partly of insoluble strands instead of one set being composed of soluble strands and the other of insoluble strands, as in the case of The covering IB responds to a treatment by solvent for the soluble strands in a similar manner but to a lesser extent than in the case of a covering all of the strands of which are soluble. As indicated in Fig. 4, the partially disolved soluble strands coalesce to some extent, especialg ly where they pass between the insoluble strands as atjll. and the material dissolved from them permeates and is absorbed by the insoluble strands which, when the solvent has evaporated, become lsubstantially encased in the re-soudmed material derived from the soluble strands. As the insoluble strands-in this example are unaffected by the solvent, the treated covering retains` more of its original fabric lappearance than would be the case if all of the strands were soluble, as in the case of the coverings shown in Figsel and 3.

`While a covering consisting of a single layer of fabric is adequate for many pume's, it is desirable for othersto provide a covering having a plurality of superimposed fabric layers whereby the strength and effectiveness of the covering is inner one l26 of which is composed of strands of soluble fibers s and the outer one 28 of insoluble fibers i. These layers are illustrated in Fig. 6 as being formed about a rod-like article or a-conductor 3l an"d as having been treated with a solvent forthe soluble strands. Thus,A the .strands of the inner fabric layer 26, as a result of being treated with solvent, coalesce and are united with each other by a homogeneous web formed-by solid material dissolved from these strands. 'Ihe aforesaid solution, however', in itsviluid state, permeates, to some extent if not completelyl the outer fabric layer 28, thereby binding the two layers together when the solution solidies. 'I'he resulting covering, therefore, retains substantially all of itsoriginal fabric appearance, the outer fabric layer 2l not having been changed much in appearance by the action of the solvent, and the inner'layer 28 provides a substantially homogeneous, impervious sheath for the conductor lll beneath it with which the inner layer 2i is also intimately connected by the aforesaid web.

Fig. 7 represents another multiple-layer fabricl covering which is illustrative of coverings of a type having two-or more layers of soluble or insoluble strands, successive layers of like strands being separated by a layer composed of strands of the other kind. In the covering illustrated in Fig. 7 the outer layer 32 and an inner layer Il are both` composed of strands of insoluble bers i andan :intermediate layer 36 is composed of strands of soluble fibers s. However.' as indicated above, the positions of the layers of soluble and insoluble strands might be interchanged. As a result of treating a covering of the type illustrated in Fig. rl with a solvent for the soluble -strands s of the intermediate fabric layer 38, the

inner and outer fabric layers 32 and 34 of insoluble strands are securely bound to the intermediate Vlayer 36 by the web of material which is dissolved from the soluble strands by the solvent employed. All of the layers oi' this covering are thus united and the outer and inner layers are u. encased by the solid material derived from the soluble strands.

Although the ,solvent treatment given to the coverings described with reference to Figs. l, 4, 6,-

and 7 hasbeen referred to as being carried out after the covering has been formed about the article, wire or conductor to be Vculvered, the invention in the method aspect also contemplatesjcoating the member to be covered with a solvent and then applying the covering to the coated member while the solvent is in afluid condition. This coating may include a plasticizer or may be constituted by a solution of the material of which the soluble strands of the covering are composed if the resulting covering is to be used in any application requiring great resiliency or toughness. 

